J. Nannoplankton Res. 37 (1), 2017, pp.61–66 © 2017 International Nannoplankton Association
ISSN 1210-8049 Printed by The Sheridan Press, USA

61

Acadialithus, a new nannofossil genus from offshore
Eastern Newfoundland, CanadaRichard W. Howe*
36 Waverley St, South Perth, WA, Australia; *richard.howe@yahoo.com
Manuscript received 11th January, 2016; revised manuscript accepted 19th December, 2016

Abstract A new nannofossil genus, Acadialithus, and two new species, A. dennei and A. valentinei are describedfrom late Tithonian aged sediments of offshore eastern Newfoundland, Canada.

Keywords calcareous nannofossils, taxonomy, new genus, new species, Canada, Newfoundland, Acadialithus,
Tithonian

1. Introduction
A new nannofossil genus, Acadialithus, and two new species, A. dennei and A. valentinei, were observed during
routine analysis of nannofossil samples from late Tithonian aged sediments from open file exploration wells from
offshore eastern Newfoundland, Canada.
2. Materials and methods
Core and ditch-cuttings samples from two exploration
wells offshore eastern Newfoundland, Canada werestudied for nannofossil biostratigraphy. The two wells
are Panther P-52 (UWI 300P524710047300), drilled by
Husky and others in 1985–1986, and Baccalieu I-78 (UWI300I784800046000), drilled by Esso and others in 1985.
Standard smear slide techniques (Bown & Young, 1998)
were adopted for the preparation of slides, which wereanalysed using a Zeiss Axiophot microscope at x1250
magnification. The photographs were taken using anOlympus DP-72 digital microscope camera with Olympus
CellSens software. The photographs are unprocessed andare presented at 2500x magnification. The samples studied
are available in the collection of the Canada Newfoundland and Labrador Offshore Petroleum Board (CNLOPB),
in St John’s, Newfoundland, Canada (http://cnlopb.nl.ca).
3. Biostratigraphy
The samples studied yielded moderately well preserved(with minor etching and/or overgrowth on most specimens,
which did not prevent their identification) and moderately
high diversity assemblages. Nannofossil abundance fluctuates from sample to sample, but is generally high (>500
specimens per 100 fields of view). Watznaueria barnesiae
is the most abundant form recovered. Associated species
include W. fossacincta, Polycostella senaria, Cyclagelosphaera margerelii, Polypodorhabdus escaigii, smallNannoconus spp., W. britannica and W. frequens. The
late Tithonian age is based on the presence of consistent
to common Polycostella senaria (Bralower et al., 1989;
Casellato, 2010), which here includes all of the hexaliths
with straight-sided (Hexalithus strictus Bergen, 1994,
junior synonym H. geometricus Casellato, 2010), concave(Polycostella senaria Thierstein, 1971) or convex (H. noeliae Loeblich & Tappan, 1966) element peripheries, in theabsence of Micrantholithus parvistellatus Varol (1991).
The Polycostella senaria group of hexaliths occur
from a level in the Tithonian above the base of P. beckmannii and range up into the Lower Berriasian (Braloweret al., 1989, Bergen, 1994), but are only common in theUpper Tithonian (clearly seen in the distribution charts in
Bralower et al., 1989). Micrantholithus parvistellatus wasdescribed by Varol (1991) as common in Lower Berriasiansediments from Irian Jaya in Indonesia. This species has
only rarely been recorded since, but is common in thestudied sections (along with diverse Lower Berriasianassemblages including Nannoconus kamptneri kamptneri,
Rhagodiscus nebulosus and Tranolithus incus) immediately above where the P. senaria group is common.
4. Systematic palaeontology
In this section a new genus Acadialithus and two new species
A. dennei and A. valentinei are described.
Acadialithus n. gen.
Derivation of name: Acadia (French): parts of the former
French colonial empire in Atlantic Canada.
Diagnosis: Nannoliths with a vertical wall made up of two
vertically stacked cycles, with six to seven elements ineach cycle. A wide central opening is present.
Type Species: Acadialithus valentinei n. gen., n. sp.
Description: Calcareous nannofossil having a verticalwall with two cycles which are made up of six to sevenelements. No structures were observed in the large central
opening. The heights of the two cycles are approximately
equal. The elements in the cycles of the wall are verticalto slightly inclined. The elements in the cycles of the wall
are roughly L-shaped in plan view, with one end of theelements extending outward to form a lateral projection ofthe element, where two elements are joined. In plan view,the lateral projections of each element in the upper cycle
project at the opposite end of each element, compared tothe lateral projections of the underlying elements of thelower cycle (see Figure 1 and Plate 2).

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Howe

PLAN VIEW OFCALCITE C-AXES
UPPER
WALL
CYCLE

LATERAL
PROJECTIONS

LOWER
WALL
CYCLE

WALL
ELEMENTS
A. OBLIQUE VIEW

B. PLAN VIEW

SIDE VIEW OFCALCITE C-AXES

C. SIDE VIEW
Figure 1: Schematic model of Acadialithus valentinei n.gen, n. sp. to illustrate the authors understanding of the structure of the genus. A. Obliqueview, showing the upper and lower cycles of wall elements and the lateral projections present on each wall cycle element. B. Plan view, showing theinterpreted orientation of the calcite c-axes of the elements in the upper wall cycle. C. Side view, showing the interpreted orientation of the calcite
c-axes of the elements in the upper and lower wall cycles

From plan view observations with a quartz plate, thec-axes of the calcite crystal comprising each element are
oblique at an angle of ~30° to the long axis of the element(Figure 1). This is clearly demonstrated in the specimen
shown in Pl. 1, figs 19–20, and Pl. 2, figs 1–2 (all of thesame specimen). This specimen has an isolated single
cycle of A. valentinei n. sp. seen in plan view. The elementsin this specimen, which are dark under crossed-polarisinglight (labelled “A” in Pl. 2, figs 1–2), are not parallel to thepolarising axes (as they would be if the c-axes in these elements were tangential) but at an angle of ~30°. The speciesof the genus are identified based on the number of elementsin each cycle.
Remarks: The oblique orientation of the calcite c-axesof the wall elements in plan view is very unusual, being
unlike most heterococcoliths, which have radial to
sub-radial distribution of c-axes in plan view, and unlike
most nannoliths, which have tangential to sub-tangential
c-axes in plan view. The unusual c-axis orientation ofAcadialithus suggests that it is unlikely to be closely
related to either heterococcoliths or to the major Upper
Jurassic to Lower Cretaceous nannolith groups, such as

the families Nannoconaceae, Braarudosphaeraceae andPolycyclolithaceae.
Acadialithus differs from members of the family Polycyclolithaceae by the orientation of the wall elements,
and in the absence of a diaphragm. Both cycles in species belonging to the Polycyclolithaceae are made up ofelements with tangential c-axes in plan view, in contrast
to Acadialithus, where the elements in both cycles haveoblique c-axes in plan view. No members of the family
Polycyclolithaceae are known from the Berriasian or older.
The families Braarudosphaeraceae and Nannoconaceae both feature radial elements with tangential c-axes inplan view. Both families feature multiple cycles of stacked
elements in plan view, unlike the two cycles seen in Acadialithus. Acadialithus is distinguished from the superficiallysimilar Lower Cretaceous genus Trapezopentus Wind& Čepek (1979) by having two cycles of elements and ahexagonal or heptagonal outline in plan-view. The latter
genus has a single-cycle wall and is strongly pentagonal inshape. Moreover, no lateral projections were noted in theelements in Trapezopentus Wind & Čepek (1979), as areseen in Acadialithus. With no clear affinities to any known

Acadialithus, a new nannofossil genus…

coccolith or nannolith families, it is possible that Acadialithus is the only member of an extinct family.
Acadialithus has been observed in Upper Tithonian
sediments from offshore eastern Newfoundland, Canada(this study), from the Baltimore Canyon area, offshore of
the northeast coast of the United States (Valentine, 1980),
offshore in the eastern Gulf of Mexico (Rich Denne, Jim
Pospichal pers. comm.), and from the Pernik District ofBulgaria (Sinnyovsky, 2005).
Acadialithus dennei n. gen., n. sp.
Pl. 1, figs 1–14; Pl. 2, figs 9–16
Brachiolithus? sp. “hexagonal form” Valentine (1980),plate 2, fig. 2
Genus et species indet. Sinnyovsky (2005), plate 2,figs 26–28
Derivation of name: In honor of nannofossil specialist
Richard Denne, Texas Christian University, Dallas, Texas,USA, who has observed this species offshore in the eastern Gulf of Mexico.
Diagnosis: A species of Acadialithus having six elementsin each cycle of the wall.
Holotype: Pl. 1, figs 1–2.
Paratype: Pl. 1, figs 3–4.
Type Level: Upper Tithonian.
Type Locality: Panther P-52 exploration well, cuttings
sample at 2780–2790m, Jeanne d’Arc Basin, offshore east
coast of Canada.
Dimensions of holotype: Maximum diameter (includinglateral projections) = 8.8µm. Diameter of the central opening = 3.6µm. Width of the wall = 2.6µm.
Remarks: Acadialithus dennei n. gen., n. sp. differsfrom A. valentinei n. sp. by having six elements in eachcycle of the wall, rather than the seven elements ofA. valentinei. Valentine (1980) recorded both A. dennei andA. valentinei n. sp. as a “common constituent” (Valentine,1980, p. 74) from samples (12,700 to 13,240’) that heregarded as Berriasian. This interval also contains Polycostella senaria, so it is here regarded as Upper Tithonian.
Unfortunately, Valentine (1980) did not present a detailed
distribution chart for the COST B-3 well. Sinnyovsky(2005) records both A. dennei and A. valentinei n. sp. as
common from sample Be 263, near the top of the Upper
Tithonian.
Acadialithus valentinei n. gen, n. sp.
Figure 1; Pl. 1, figs 15–20; Pl. 2, figs 1–6
Brachiolithus? sp. “septagonal form” Valentine (1980),
plate 2, fig. 1
Genus et species indet Sinnyovsky (2005), plate 2, fig 29
Derivation of name: In honor of nannofossil specialist
Page C. Valentine, United States Geological Survey, California, USA, who figured specimens of Acadialithus dennei n. sp. and A. valentinei in Valentine (1980).
Diagnosis: A species of Acadialithus with seven elementsin each cycle of the wall.

63

Holotype: Pl. 1, figs 15–16.
Paratype: Pl. 1, figs 17–18.
Type Level: Upper Tithonian.
Type Locality: Baccalieu I-78 exploration well, 3287.18m,
offshore eastern Newfoundland, Canada.
Dimensions of holotype: Maximum diameter (includinglateral projections) = 8.0µm. Diameter of the central opening = 4.4µm. Width of the wall = 1.8µm.
Remarks: Acadialithus valentinei has seven elements ineach cycle of the wall rather than the six elements of A.
dennei n. sp.
5. Discussion
It is intriguing that a large and distinctive nannofossil,
which can be present in high abundance (1–5 specimens
per field of view at 1000x), and with a broad geographic
distribution, has been so rarely recorded previously, despite
many detailed nannofossil studies of the Upper Tithonian
interval (Thierstein, 1973, Roth, 1983, Roth et al., 1983,Rahman & Roth, 1991, Bralower et al., 1989, Casellato,2010, Bergen et al., 2013). The fact that Acadialithus
has been recorded in the Upper Tithonian in the Atlantic
Ocean basin, in the high-latitude, cool surface-water ofoffshore Newfoundland area, the mid-latitude Baltimore
Canyon area, and the low-latitude, warm surface-water
eastern Gulf of Mexico suggests that the genus does nothave a strongly temperature-controlled distribution.
With the intensive study given to the Tithonian/Berriasian boundary interval in Deep Sea Drilling Project Hole534A, offshore Florida (Roth, 1983, Roth et al., 1983,Bergen, 1994, Bralower et al., 1989, Rahman & Roth,1991, Casellato, 2010, Bergen et al., 2013), if Acadialithus
is present in this well, it must be extremely rare, or more
likely, absent. As Acadialithus has a short range within thelate Tithonian, the absence of any species of this genus inDSDP Hole 534A suggests that there may be missing section in the Upper Tithonian in this well. This missing section
may be widespread throughout the Atlantic Ocean basin.
6. Acknowledgements
I am grateful to Richard Denne (Texas Christian University, Dallas, USA), Robert Campbell (Shell, Houston,USA), Jim Bergen (Paleo in the Hill Country, Brenham,USA), Kevin Cooper (RPS Energy, UK), Kristalina
Stoykova (Bulgarian Academy of Sciences, Bulgaria) andJim Pospichal (Bugware, Tallahassee, USA) for helpful
discussions on the taxonomy and biostratigraphy of Acadialithus. I’m also very grateful to Paul Bown and Emanuela Mattioli for their constructive reviews.
References

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fossils from the Vocontian Trough (SE France) and DeepSea Drilling Site 534: new nannofossil taxa and a summary of low-latitude biostratigraphic events. Journal ofNannoplankton Research, 16: 59–69.

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western North Atlantic. Eclogae Geologicae Helvetiae,
84: 765–789.
Roth, P.H. 1983. Jurassic and Lower Cretaceous calcareous
nannofossils in the western North Atlantic (Site 534):
biostratigraphy, preservation, and some observations onbiogeography and palaeoceanography. Initial Reports ofthe DSDP, 76: 587–621.
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from Deep Sea Drilling Project Site 534A. Initial Reports ofthe DSDP, 76: 573–579.
Sinnyovsky, D.S. 2005. Upper Tithonian-Berriasian calcareous nannofossil zonation of the turbidite deposits of Kotel Formationnear Berende village, Pernik District. Annual of the Universityof Mining and Geology “St. Ivan Rilski”, 48(1): 129–135.
Thierstein, H.R. 1971. Tentative Lower Cretaceous Calcareous
Nannoplankton Zonation. Eclogae Geologicae Helvetiae,64: 459–488.
Thierstein, H.R. 1973. Lower cretaceous calcareous nannoplankton biostratigraphy. Abhandlungen der Geologischen
Bundesanstalt, 29: 3–52.
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paleoenvironments, and post-Jurassic continental margindevelopment. In: P.A. Schollev (Ed.). Geological Studiesof the COST No. B-3 Well, United States Mid-AtlanticContinental Slope Area. United States Geological Survey
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Acadialithus, a new nannofossil genus…

65

Plate 112

31-2. Acadialithus dennei n. sp. Holotype

3-4. A. dennei n.sp. Paratype57

Panther P-52 2780-90m

Panther P-52 2780-90m

65-6. A. dennei n.sp.

Panther P-52 2780-90m

10119-10. A. dennei n.sp. side view

Panther P-52 2780-90m

141513-14. A. dennei n.sp. side view

1615-16. A. valentinei n. sp. Holotype

Panther P-52 2780-90m

171211-12. A. dennei n.sp. side view

Panther P-52 2780-90m

1387-8. A. dennei n.sp.

Panther P-52 2780-90m

94Baccalieu I-78, 3287.18m

181917-18. A. valentinei n. sp. Paratype2019-20. A. valentinei n. sp. Isolated single cycle

Baccalieu I-78, 3287.18m

Baccalieu I-78, 3287.18m
10um

all photos 2500x
Plate 1: Light microscope photographs. PL = plain light; XPL = cross-polarised light; QPL = cross-polarised light with quartz plate. Columns 1, 3 in
XPL. Columns 2, 4 in QPL

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HowePlate 2AAA1231-2. A. valentinei n. sp. Isolated single cycle (same specimen asPl. 1, figs 19-20). Dark elements labelled “A”). Baccalieu I-78, 3287.18m

543-4. Acadialithus valentinei n. sp. side view
Baccalieu I-78, 3287.18m

675-6. Acadialithus valentinei n. sp. side view

83-4. A. valentinei n. sp. side view

Baccalieu I-78, 3287.18m

Baccalieu I-78, 3287.18m

9101179-10. Acadialithus dennei n. sp. Focus on upper cycle

12811-12. A. dennei n.sp. (same specimen as figs 9-10). Focus onlower cycle. Baccalieu I-78, 3287.18m

Baccalieu I-78, 3287.18m.

ABA

BA
1315

141615-16. A. dennei n.sp. (same specimen as figs 9-10).
Focus on lower cycle. Elements clearly belonging to upper cycle
labelled “B” on fig. 15, plan view orientation of c-axes labelled on
fig. 16. Baccalieu I-78, 3287.18m

13-14. A. dennei n.sp. (same specimen as figs 9-10).
Focus on upper cycle. Elements clearly belonging to upper cycle
labelled “A” on fig. 13, plan view orientation of c-axes labelled onfig. 14. Baccalieu I-. 78, 3287.18m
10um

all photos 2500x
Plate 2: Light microscope photographs. PL = plain light, XPL = cross-polarised light, QPL = cross-polarised light with quartz plate. Figs 1–3, 6–7, 9,11, 13, 15 in XPL. Figs 4–5, 8, 10, 12, 14, 16 in QPL